関連する実験動画
Updated: May 14, 2026

16:24
Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
超分子効果的モラリティに対する形状制限の影響の定量化
Harry Adams1, Elena Chekmeneva, Christopher A Hunter
1Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom.
Journal of the American Chemical Society
|January 31, 2013
まとめ
この研究は,超分子複合体の安定性に対する分子柔軟性の影響を定量化しています. 亜鉛ポルフィリン-ピリジン複合体の回転の自由を凍結すると,結合親和性が著しく低下し,制限された運動のエネルギーコストを強調します.
科学分野:
- 超分子化学 超分子化学
- 物理有機化学 物理有機化学
- 化学熱力学 化学熱力学
背景:
- 亜鉛ポルフィリン-ピリジン複合体は,非共性相互作用を研究するためのモデルシステムを提供します.
- 分子内水素結合は,超分子組成の安定化に重要な役割を果たします.
- 化学のダブルミュータントサイクルは,結合エネルギー貢献を解剖するための強力なツールです.
研究 の 目的:
- 亜鉛ポルフィリン-ピリジン複合体の分子内水素結合の自由エネルギー貢献を定量化するために.
- 分子内相互作用の有効なモラリティ (EM) を決定する.
- 複合体の安定性に対する分子柔軟性と溶媒の極性の影響を調査する.
主な方法:
- トゥルーエンと1,1,2,2-テトラクロロエタン (TCE) に含まれる96個の亜鉛ポルフィリン-リガンド複合体の連結定数の測定.
- 自由エネルギーへの貢献を評価するために,64の化学的ダブルミュータントサイクルの構築.
- 分子内および分子間結合定数を比較することによって有効なモラリティ (EM) を決定する.
主要な成果:
- 分子内H結合の有効モラリティ (EM) は,H結合受容体型 (アミド対エステル) と溶媒 (トルーエン対TCE) に依存していないことが判明しました.
- トルションの自由度が増えたリガンドは,硬質の同位体より数桁低いEM値を示した.
- 超分子複合体のロータを制限するエネルギーコストは,約5kJ/molであると決定されました.
結論:
- 分子の柔軟性は,超分子複合体の安定性に大きく影響し,制限された動きは,実質的なエネルギーペナルティを伴う.
- この方法論は,複雑な分子システムにおける非共性相互作用を評価するための堅固な枠組みを提供します.
- 構成制限のエネルギーコストを理解することは,新しい超分子材料と触媒の設計に不可欠です.
関連する概念動画
Determination of Molar Masses of Polymers II
Polymer samples typically consist of macromolecular chains with a distribution of lengths, resulting in a range of molar masses rather than a single discrete value. Conventional descriptors such as the number-average molar mass and weight-average molar mass quantify this distribution but do not fully capture polymer behavior in solution..The viscosity-average molar mass provides a more realistic description of polymer behavior in solution because it accounts for the enhanced contribution of...
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
Freezing Point Depression and Boiling Point Elevation
Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
Expressing Solution Concentration
A solute is a component of a solution that is typically present at a much lower concentration than the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
Concentrations may be quantitatively assessed using a wide variety of measurement units, each convenient for particular applications. Molarity (M) is a useful concentration unit for many applications in chemistry.
Concentrations may be quantitatively assessed using a wide variety of measurement units, each convenient for particular applications. Molarity (M) is a useful concentration unit for many applications in chemistry.
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
Determination of Molar Masses of Polymers I
Polymerization produces macromolecules with a range of chain lengths due to the random nature of molecular growth processes. As chains form and terminate at different stages, a single polymer sample contains molecules of varying sizes rather than a uniform structure. This variability is described using average molar masses and distribution-related parameters, which together provide a comprehensive understanding of polymer characteristics.The distribution of molar masses plays a critical role in...

